We were at Yellowstone Sept 26 through 29 last year, and Saturday the 28th was a free day there, and it was far more crowded than any other day. I'm surprised that the $25 (which Yellowstone/Grand Teton charges) makes such a big difference in how many people go, since it costs so much to get to that area in the first place and stay in motels, etc. What does the extra $25 mean when you already spent hundreds or even thousands of dollars to get there anyway?